Wavelength Dispersive X-ray Spectrometry

The wavelength range of interest in X-ray fluorescence (XRF) spectrometry is roughly the range between 0.04 and 2 nm. This allows the analysis of the elements from fluorine upward to the transuranics, either on their K or L characteristic lines. Using special precautions and dedicated multilayers (see section on “Diffraction and the Analyzing Crystal”), the range can be enlarged to 11 nm, including the characteristic lines of beryllium. Energy and wavelength are related according to the following equation: E=hcλ where E is the photon energy; h is Planck's constant (6.626 10−34 J s, or 4.135 10−15 eV s); c is the speed of light in vacuum (3×108m/s); and λ is wavelength. By substituting these values in Eq 1, and expressing photon energy in kiloelectronvolts and wavelength in nanometres, the following is obtained: E=1.24λ or λ=1.24E